Kegiatan jual-beli saat ini telah banyak dilakukan secara digital atau disebut kegiatan e-commerce. Perkembangan teknologi beserta kemudahan yang diberikan menjadi alasan dari banyaknya kegiatan e-commerce yang terjadi saat ini. Kegiatan e-commerce saat ini pun telah berkembang menjadi bentuk kegiatan e-commerce lainnya, yaitu social commerce. Kegiatan social commerce saat ini juga telah berkembang menjadi berbagai macam bentuk, salah satunya adalah kegiatan community group buying berbasis chat. Penelitian ini ditujukan untuk mengembangkan kegiatan social commerce dengan fokus berupa kegiatan community group buying berbasis chat (chat-based community group buying). Aplikasi media sosial berbasis chat yang menjadi fokus utama penelitian ini adalah aplikasi LINE. Aplikasi LINE dipilih karena kondisi nyata kegiatan chat-based community group buying saat ini sudah dilakukan menggunakan aplikasi LINE beserta dengan pertimbangan lainnya terkait dengan potensi LINE sebagai media sosial berbasis chat yang mampu mengakomodasi kegiatan social commerce berupa chat-based community group buying. Penelitian ini menggunakan pendekatan user-centered design dan menghasilkan rancangan desain prototipe mobile social commerce pada aplikasi LINE yang dapat memfasilitasi chat-based community group buying. Sebanyak total 10 fitur utama dihasilkan berdasarkan riset kebutuhan pengguna, baik dari hasil analisis survei maupun wawancara. Rancangan desain kemudian dievaluasi menggunakan metode usability testing, wawancara kontekstual, kuesioner System Usability Scale (SUS), dan heuristic evaluation. Evaluasi dengan usability testing menghasilkan completion rate untuk mayoritas task sebesar 100%, serta satu task bernilai 33,33% sedangkan sedikit task yang bernilai 66,67%. Sementara itu, rata-rata skor System Usability Scale yang didapatkan dari seluruh partisipan adalah 77,6 atau grade B+. Berdasarkan analisis terhadap hasil evaluasi dari wawancara kontekstual dan heuristic evaluation, didapatkan sebanyak enam label solusi perbaikan dan tujuh label saran perbaikan.

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Many buying and selling activities are currently carried out digitally or are called e-commerce activities. Technological developments with the convenience provided are the reasons for the many e-commerce activities that are happening now. Current e-commerce activities have developed into other forms of e-commerce activities, namely social commerce. Nowadays, social commerce activities have also evolved into various forms of activity, one of which is chat-based community group buying activity. This research aims to develop social commerce activities with a focus on chat-based community group buying activities. The chat-based social media application that is the main focus of this research is the LINE application. The LINE application is selected because of the reality of chat-based community group buying activities currently done using the LINE application with other considerations related to LINE's potential as a chat-based social media capable of accommodating social commerce activities in the form of chat-based community group buying. This research uses a user-centered design approach and produces a mobile social commerce prototype design for the LINE application that can facilitate chat-based community group buying. A total of 10 main features were generated based on research on user needs, both from the results of survey analysis and interviews. Then, the designs are evaluated using the usability testing method, contextual interviews, the System Usability Scale questionnaire, and heuristic evaluation. Evaluation with usability testing produces a completion rate for the majority of tasks of 100% with for one task of 33,33%, and for minority tasks of 66.67%. Meanwhile, the average System Usability Scale score obtained from all participants was 77.6, or grade B+. Based on an analysis of the evaluation results from contextual interviews and heuristic evaluations, there are six improvement solution labels and seven improvement suggestion labels.